The following disclosure relates to electrical circuits and signal processing.
A Cartesian feedback loop can be used to improve the linearity of a radio transmitter. An example of a Cartesian feedback loop is shown in FIG. 1. The improvement in linearity allows the use of a less linear, more power efficient power amplifier 101 while maintaining the performance required by a given application.
At low output power levels, the signal in the feedback path can be amplified using an amplifier block 102 in order to improve noise and carrier leakage performance. The feedback amplifier block 102 contributes significantly to the power consumption of the system when the transmitter is operating at low output power levels.